The present invention relates to ultrasonic detection apparatus, and in particular to the field of biological detection using ultrasonic apparatus.
Ultrasonic detection has been used in a number of prior art systems for measuring or detecting physiological data within a body, either human or otherwise, by means of ultrasonic transducers external of the body. Such systems take advantage of the fact that pulses of ultrasonic energy propagated into the body will echo or reflect from various internal organs or boundaries of differing tissue structures. From a knowledge of the velocity at which the pulses are propagated in the body, it is possible to deduce the position of a particular internal portion of the body by observing the timing of the return pulse reflected from that body structure. This method has been used for example, in detecting dislocations of the brain in cases of severe head injuries.
Another use of this general method has been in the field of animal husbandry, in which ultrasonic pulsing and detection has been used for detecting pregnancies in sows and other farm animals. For many reasons it may be economically important for a livestock producer to know if individual farm animals may be pregnant. For example, such knowledge may be required in order to make a decision of whether to market the animal; whether to start it on a special feeding program; or whether to re-breed the animal during the same season.
It has been found in the prior art that an ultrasonic echo or return pulse is much stronger from the uterus of a pregnant animal than from one which is not pregnant, thus providing a basis for testing. The strong return is from the build up of amniotic fluid in the enlarged uterus which occurs during the gestation period, some time following conception. For example, in the case of sows, the build up is usually sufficient after about thirty days following conception to give a positive indication via ultrasonic detection.
One successful type of prior art ultrasonic detector for use in livestock pregnancy detection has used a cathode ray tube for displaying the echoes or return pulses received from within the animals body. The trace is swept horizontally as a function of time, while the return pulse pattern is traced out vertically. With suitable instruction, an operator can learn to interpret the traces to look for a pulse of sufficient amplitude at a given time delay from the transmission of the pulse, which signifies a pregnant condition in the animal being tested. However, each layer of skin, fat and bone, and numerous other organs will return echoes, giving rise to a multitude of spikes on the CRT display. It thus takes certain amount of training and experience, together with a certain minimum amount of time to study the oscilloscope trace in order for the operator to make the determination. Unfortunately, while the operator is trying to study the oscilloscope pattern, the animal under observation may try to squirm away from the probe placed at her belly, or at worst she may be trying to attack the probe and/or its operator. It therefore demands nearly the full attention of the operator just to maintain the probe in position, making it very difficult at best for an operator to place the probe, restrain the animal, and study the oscilloscope display.
The present invention adds to this prior art type of ultrasonic detection system by providing an automatic audible indication circuit. Through the use of the present invention, the operator is only required to position the probe on the animal, then listen for the signal tone. The presence of a tone indicates the strong return signal from the uterus, while the absence of a tone indicates that the animal is not pregnant. It is therefore only necessary to look at the oscilloscope display for marginal cases or unusual situations for example involving disease; alternatively, an experienced and knowledgeable operator can still use the display to obtain subtle, quantitative data concerning the returns, if necessary.